Panel-styled calorific devices and a process for manufacturing the same

ABSTRACT

A calorific material for panel-styled calorific devices is prepared by mixing a paste of a metal powder with a synthetic oil and firing the mixture to a temperature sufficient to melt and partially oxidize the metal. A panel-styled calorific device coated with the calorific material is prepared by coating a substrate with a paste of a metal powder and a synthetic oil, firing the coated substrate at a temperature sufficient to melt and partially oxidize the metal and coating the fired substrate with a protective material.

United States Patent 1191 Horiki 1 1 PANEL-STYLED CALORIFIC DEVICES ANDA PROCESS FOR MANUFACTURING THE SAME [76] Inventor: Seinosuke Horiki.57-134 Horagai.

Narumi. Midori. Nagoya. Japan [221 Filed: Dec. 20. 1973 1211 Appl. No.;426.596

130] Foreign Application Priority Data Dec. 211 1972 Japanv.--17-1-17139 Dec. 26. 1972 Japan t v v 48-1831 Apr. 15. 1973 Japan48-42541 1521 Us. C1. 428/426; 427/1231427/125; 428/457 [511 int. (11.8323 17/06; 344D 1H8. B44D 1/16 [58] Field of Search 117/217. 218, 227'.219/543. 338/308. 309

[561 References Cited UNITED STATES PATENTS 2.882.187 4/19591\'\\ate.....v.,,,..... 117/215 2.8911228 6/1959 Smithdohannsenh...117/227 3.048.914 8/1962 Kohriligmnnu. 117/2115 3.052.573 9/1962Dumesnil i .7 117/221 1 1 Nov. 11,1975

3.079.282 2/1963 Haller et 111.... 117/227 3.11)).75-1 11/ 1963 Tielenset a1. v 117/218 3.20 7116 /1965 Hoffman 117/227 3.277.419 111/1966But1..,..,...,...,..... 338/314 3.296.415 1/1967 Eisler 219/3853.374.111) 3/1968 Miller 117/227 3.385.799 5/1968 Hoffman... H 117/2273.3961155 7 /1968 Hedden et a1, 117/227 3.679.473 7/1972 Blatcht'ord eta1v 117/217 3.808.046 4/1974 Dine) 117/227 Primal) limminvr-Cameron K.weiffenlmch Artur/1e Age/i1. or l-'1'rmOh1on. Fisher. Spit-alt.McClelland it Maier 1571 ABSTRACT A calorific material for panel-soledcalorific devices is prepared by mixing a paste of a metal powder with asynthetic oil and firing the mixture to a temperature sufficient to meltand partialh oxidize the metal. A panel-styled calorific device coatedwith the calorific material is prepared h coating a substrate with apaste of a metal powder and a s nthetic oil. firing the coated substrateat a temperature sufficient to melt and partially oxidize the metal andcoating the fired substrate with a protective material.

8 Claims. 4 Drawing Figures US. Patent Nov. 11, 1975 3,919,441

FIG. I

PANEL-STYLED CALORIFIC DEVICES AND A PROCESS FOR MANUFACTURING THE SAMEBACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention relates to panel-styled calorific devices. More particularly.the invention relates to panel-styled calorific devices are well suitedfor heating both large and small areas because there is a lesser risk ofdisconnection with these devices and because they have a simplerconstruction than other line-styled calorifie materials.

2. Description of the Prior Art Hitherto a wide variety of paneI-sty ledcalorific devices have been known. Many types of calorific panels areknown in the prior art. One style comprises a sub strate coated with amixture of carbon powder in a binder. However. the relative uniformityof the film of this type of panel is poor which results in turbulance ofthe electric resistance and the calorification process. Another style ofpanel comprises a substrate which has been coated with a metal film byvacuum evaporation of a metal. However. it is difficult to obtaincalorific panels of relatively large areas because of difficultiesencountered with vacuum evaporation of the metal. Also the cost of thistype of panel is high. Yet another style of panel comprises a substratewhich is covered with sheafs of fine metal wires. However. themanufacturing cost of this type of panel is high since a series ofcomplicated process steps must be used which involve the fabrication ofmetal into the proper sized wire. a step of braiding the wire andsheafing it into panel form and other complicated steps.

Currently in use on the market are conductive inks which comprise amixture of a metal such as silver or some other noble metal in avitreous glass frit. This ma tcrial can then be spread over thesubstrate and then fired to form a conductive layer over the substrate.The metal used in the conductive ink should be one which is resistant tooxidation during the firing of the substrate. Thus. silver or anothernoble metal is required which greatly raises the expense of the device.

To overcome this difficulty. it is disclosed in US. Pat. No. 3.647.532that a conductive metal layer can be formed over a substrate byspreading a conductive ink which comprises a metallic powder such ascopper suspended with a glass frit in a fugitive or temporary or ganicbinder preferably ith a reducing compound on a refractory substrate. Theuse of this procedure eliminates the need for a noble metals andoxidation and an otherwise inert atmosphere can be avoided. Thus. thistechnique permits the use of lower cost metals such as copper. nickel.cobalt and the like. This latter observation has led to the presentinvention which satisfies the need for low cost and easily constructedpanel-styled calorific devices by the discovery that if the metal in theapplied calorific layer is allowed to partially oxidize during firing ofthe substrate. a calorific layer of a high degree of resistance can beobtained because of the partially oxidized metal. Thus. it is quiteunnecessary in the present invention to deliberately use a metalresistant to oxidation. or to fire the coated substrate in anon-oxidizing atmosphere.

SUMMARY OF THE INVENTION Accordingly. one object of the presentinvention is to provide a panel-styled calorific device which is easilyproduced at low cost.

Another object of the present invention is to provide a panel-styledcalorific device which is durable and useful in many applications.

Yet another object of the present invention is to provide a panel-styledcalorific device which has substantial heat retaining properties andregenerative capacitics.

Still another object of the present invention is to provide an efficientmethod for producing panel-Sty led calorific devices.

Briefly. these objects and other objects of the present invention ashereinafter will become more readily apparent can be attained by acalorific material for panelstyled calorific devices which is preparedby mixing a paste of a metal powder with a synthetic oil and firing themixture to a temperature sufficient to melt and partially oxidize themetal. A panel-styled calorific device coated with the calorificmaterial is prepared by coating a substrate with a paste of a metalpowder and a synthetic oil. firing the coated substrate at a temperaturesufficient to melt and partially oxidize the metal and coating the firedsubstrate with a protective material.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of theinvention and many of the attendant advantages thereof will be readilyobtained as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings. wherein:

FIG. 1 is an illustration of the longitudinal section of the panelstyledcalorific devices of the present invention'.

FIG. 2 is a partial sectional view of the calorific device of thepresent invention:

FIG. 3 is a partial sectional view of another embodi ment of thecalorific device of the present invention; and

FIG. 4 illustrates an example of a circuit plan used to activate thepanel-styled calorific device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred metalswhich are used in the calorific material of the invention are thosewhich have practical firing temperatures. i.e.. a melting point of lessthan l.1(]OC. Since the protective coating films which are applied overthe calorific layers are used to prevent the calorific layer fromcontacting air and oxidizing. plastic or vitreous glass meterials shouldprimarily be employed. The most preferred materials are silicone resins.melamine resins. low melting point glass frits and the like. Theapplication of certain types of porous layers placed over the filmsubstantially improve the heatretaining properties and regenerativecapacity of panelstyled calorific layers.

Generally. the calorific devices are fabricated from a paste which isformed by milling a mixture of a metal powder and a glass powder with asynthetic oil which contains an undiluted synthetic resin solution. Thepaste which is formed is applied to a substrate as a film 3 of paste.Thereafter. the film is tired to form a calorific lay er on thesubstrate. Subsequently. a paint containing a plastic or a plastic filmis applied over the calorific layer to form an insulating coating layer.

Two procedures are used for applying a film of paste to the substrate.One procedure employs the direct spreading of the paste on thesubstrate. The other procedure involves the transfer of the paste from aprinting paper covered with the paste. Of the two ways. a uniform filmcan be rather easily obtained by the transfer method. especially whenthe surface of the substrate is curved. Thus. it is essential that thefilm be flexible in order to exactly adapt to the curved surface. It isdesired that the synthetic resins which comprise the synthetic oil havea glass transition point below 20C.

With reference to FlG. l and FIG. 2. the panel-styled calorific deviceconsists of a substrate 1 l. a calorific lay er 12 formed thereon. and acoating lay er 13 which protects the calorific layer 12. Both ends ofthe calorific layer 12 are equipped with zonal electrodes l4 andelectric wires 15 connected to electrodes 14. Calorific layer 12. asshown in FIG. 3. may also be arranged as strips of material on thesurface.

Substrate 11 is fabricated from insulating materials which are capableof being fired at temperatures at which calorific lay er 12 is formed.Suitable substrates include ceramics. glass. bricks. pottery material.gypsum. calcium carbonate. calcium silicate. asbestos and the like.These materials are usually formed in the shape of boards or otherdesired shapes such as dishlike. cap-like. or tube-like forms. Alsosuitable for use are fibers of ceramic or glass materials which areknitted or bonded. Further. if the panel is to have only one calorificlayer 12. the structure of the substrate ll can be modified to comprisean ordinary metal panel which is enameled with a glass or ceramiccoating on the side of the metal surface which has the calorific layer.Such enameled metal panels are the most preferred materials forsubstrates. because the glass or ceramic layer is reinforced by themetal base. and the calorific layer 12 which coats the enamel layer.readily adheres to the substrate. In addition. because the problem ofthermal strain is not always avoidable for calorific devices. the glassor ceramic laycr serves as a buffer zone between calorific layer 12 andits metal base. This being the case. the use of enameled metal panels assubstrates yields products of good durability. great mechanical strengthand which are capable of being rapidly heated and cooled.

The materials which are used in calorific layer 12 are fired productsofmetals or mixtures of metals and glass. Any kind of metal can be usedto produce the mixtures to be fired if they have the properconductivity. However. it is preferred that materials have a meltingpoint of less than l.l()UC. preferably about 400C. as far as possible inorder to facilitate the firing process hereinafter described. Suitablemetals include copper. silver. gold. zinc cadmium. aluminum. indium.thallium. tin. lead. antimony. bismuth. and the like. Some of thesemetals have melting points greater than l.lO()C. However. the objectiveof the invention can still be achieved with the high melting metals ifthe firing termperatures are elevated. Another way to circumvent theproblem of the high melting metals is to blend a metal with a meltingpoint below l.100C with a metal having a melting point above l.l0()C.The combined metals will then have a eutectic or melt-adhesivetemperature Ill 4 below l.lUUC. Thus. the problem presented by the highmelting metals can be solved by either technique.

Of the suitable metals mentioned. Zinc. tin. and lead are the mostpreferred from the view-point of their behavior when fired and theircost. lt has been found tha when the metals are partially oxidizedduring the firim process. thereby achieving the desired electricalresistance. better results are attained when the metal is blended withan amount of metal oxide before tht metal is fired.

With reference to the glass used in the mixture which is fired. almostany kind of ordinary glass can be used if it contains a skeletalcomponent of silicic acid. phos phoric acid. boric acid or the like andan additive such as an alkali metal. and alkali earth metal. lead. an:or the like.

In the metal-glass fired products. the metal component is the conductivecomponent. and the metal oxide and glass components constitute theinsulating materials. In order to achieve the desired level ofresistance- -normally from several Kit/sq cm and to several Sl/sq cm onthe metallic component of the mixed components should be present inquantities between 97 to 27% by weight. If the metal component in themixed fired product exceeds this range. the resistance becomes smallerand it will be all the more difficult to achieve good calorification. Onthe other hand. if the metal content is below this range. the resistanceincreases and the free flow of the electric current is diffi cult. Inview of the fact that voltages between 100 and 200 volts are commonlyused in the home. it is generally desirable that the metal content ofthe mixed fired products be within the range of to 40%. lt is especiallypreferred that the metal content range from 90 to 70% by weight.

Of course. the resistance of the mixed fired product or calorific layeralso depends upon the thickness of the calorific film. By taking intoconsideration such factors as the case of production as hereinafter willbe more fully described and the durability of the final products. themost favorable thickness of the calorific film ranges from several tenup to several hundred microns. By considering all of these factors. thedesired resistance values for the calorific devices can be attained.

The protective coating layer 13 is formed from various insulating.heat-resistant materials. and therefore includes the same materialswhich are used for substrate 11. Since the protective coating is appliedafter calorific layer 12 is applied to the substrate. it is notnecessary to fire the calorific layer. nor to use such heat-resistantmaterials as used for substrate 11. Consequently. it is possible to usemany kinds of heat-resist ant plastic materials such as tcflon resins.silicon resins. aminoplast resins. epoxide resins. urethane resins.polyamid resins. polyimide resins. polydiphenyl ether resins. andpolymers which contain copper. boron. titanium or aluminum and so on.Moreover. in the case when the calorific material is required to retainheat at temperatures less than C. plastic materials such as polyvinylchloride. polyvinylidene chloride. nylon. acrylic resins. syntheticrubber. natural rubber and the like are suitable as protectivematerials. In view of the heat-retaining and exothermic properties ofthe calorific device inorganic foaming materials such as ceramics.glass. gypsum board. calcium carbonate board. calsium silicate board.sirasu board and the like or inorganic heat-resisting porous materialssuch as inorganic textile fabrics. knitted from glass and ceramic fibersare very suitable materials.

As far as the cost and heat-resisting properties of the protective layerare concerned. arnino plast resins such as melamine resins. urea resins.benzoguanamine resins and the like are also very desirable.

For the manufacture of the panel-styled calorific materials of thepresent invention it is preferred that the manufacturing processhereinafter described be used.

Initially. a metal powder or a mixture of glass powder and a metalpowder is suspended in a synthetic oil which is composed of a syntheticresin solution. In the suspension it is preferred that the particle sizeof the metal powder be about to 50 u and that the particle size of theglass powder be about l0 to uv If the particle size of the powders istoo fine. trouble will be encountered in the milling operation and filmsof uniform thickness will be difficult to attain.

Suitable synthetic resins which can be used for synthetic oils includemany different types of resins such as vinyl. polymers or denaturedvinylpolymers such as acryl resins. methacrylic resins. vinyl acetateresins. styrol resins. vinyl ether resins. vinyl chloride resins.vinylidene chloride resins. vinyl pyrrolidone resins. polyethylene.polypropylene. polyvinyl alchohol. acetal resins. butyryl resins and thelike; condensation polymers such as phenol resins. alkyd resins.melamine resins. polyamide resins. polyurethan resins. and the like.cellulose derivatives such as methylcellulose. hydroxyethyl cellulose.carboxymethyl cellulose. ethylcellulose. cellulose nitrate. celluloseacetate. cellulose butyrate and the like. rubbers such asstyrenebutadiene rubber. acrylonitrile-butadiene rubber. isoprenerubber. butyl rubber. polybutadiene polychloroprene. ethylene-propylenerubber. thiokol rubber. natural rubber.

and their reclaimed rubbers; and petroleum resins. cumarone resins.terpene resins. rosin and derivatives thereof. starch. denatured starch.proteins. denatured protein and the like. Other resins. too numerous tomention are also suitable resinous materials.

Of the synthetic resins mentioned. it is possible to mix two or more ofthe resins together to form a suitable oil. If desired. other componentssuch as plastisiz ers. decomposition promotors. reducing agents andothers can be added to the oil.

When the calorific layer is applied to or printed on the substrate. thepresence of one of the resinous materials in the applied compositiontends to cause tackiness of the printed layer which makes handlingtroublesome. In order to remedy this difficulty the use of materialswhich have a Tg (glass transition temperature) greater than 30C isrecommended. In view of the firing and oxidation temperatures employedfor the metals in the process of making the calorific devices. resinoussubstrates which decompose below 600C are preferred. However. none ofthese limitations are critical because. for example. the tackiness ofthe resin used can be eliminated from resins having a Tg of 30C or lowerby the use of bridging.

The synthetic resins mentioned above as synthetic oils are readilyavailable on the market in many different solutions of organic solventssuch as toluene. xylene. ethyl acetate. butyl acetate. cellosolveacetate. butyl cellosolv'e. acetone. methyl ethyl ketone. naphtha. pineoil and the like and emulsified aqueous solutions. These solutions oremulsions are usually applied to the substrate with synthetic resinconcentrations of about 30 to 609! by weight.

The previously described metal and glass powder mixtures and a syntheticoil are blended together by a ball mill. a roller mill. an attriter. amasher. or the like until a paste is formed.

The composition of the paste may be altered to conform to the resistancelevels required for the resultant calorific layer. Specifically. it mustbe taken into consideration that when the coated device is fired. theresistance value of the calorific layer will decrease with increasingmetal content. However. even when the metal content of the paste issubstantial. the resistance value of the layer will increase as theyield of metal oxidation product increases under more and more severefiring conditions.

In order that the calorific layers which are produced under the firingconditions of the invention. i.e.. as a result of firing at atemperature of about l.(J00C for about I hour in air. have a quantity ofmetal which is sufficient to maintain the resistance values of the layerwithin the range of from several Q/sq cm to several KQ/sq cm. thequantity of miscible glass powder should be kept below 60% by weight. Atthese levels of glass powder. it doesn't matter if only metal powder ispres ent without relatively large amounts of glass powder.

The ratio of synthetic oil to metal or a mixture of metal and glassdepends on the film thickness. substrate species and the like. Usually.however. a ratio of 10 to 60 parts by weight synthetic oil per 700 partsby weight of the metal or metal-glass mixture is employed. The ratio isdetermined by the plastering working property of the paste. lfthe amountof synthetic oil exceeds the indicated ratio. slackening of the pastewill result and the paste will turn up when applied during plasteringbecause of the low \iscosity of the mixture. If the amount of the oil isless than the indicated ratio. the oilmetal mixture is difficult topaint because the viscosity is too high.

The paste may be applied directly to the substrate surface by means of.for instance. silk screen printing. When the substrate surface iscurved. however. it is more advantageous to adopt the so-called decaltransferring method in order to more easily obtain a uniform paste film.In this'case. it is desirable that the film of paste plastered on theprinting paper be flexible for good working properties during thetransfer process. The glass transition point (Tg) of the syntheticresins which comprise the synthetic oil should be less than 20C in orderthat said film may be flexible. because if the synthetic resin having aglass transition temperature of more than 20C is used. the printinglayer is likely to loose its flexibility. readily crack. and loose itsadaptability to various shapes of substrate surfaces. For the samereasons it is desired that the Tg of the mixture be below 20C when thesynthetic resins are mixed.

When the synthetic resins are being mixed. Tg temperatures of themixtures less than 20C are satisfactory. In order to determine the Tg ofthe mixtures. the following formula is used:

TgaMa+TgbMb Tga+b.

wherein:

Tga the glass transition point of component A; Tgb the glass transitionpoint of component B; Ma the molar fraction of component A: and Mb themolar fraction of component B. In the transfer step ordinary paper canbe used. However. the more preferable substrates are releasing papers orpapers painted with a water soluble glue. Nor- 7 mally screen printingis used to print the paste on the transfer papers.

After paste printing. an over-print laquer may be further applied on thesurface of the printed layer to protect it. For the base material of theover-print lacquer. it is advisable to choose a synthetic resin from thesame group of synthetic resins with Tg temperatures below 20C ifpossible as the raw material for the synthetic oil of the presentinvention. The printing layer thus obtained can then be transferred ontoa substrate which is insulated. on its surface by a material such as aceramic. steatite. forsterite. an aluminum coated oxidized film. glass.ceramic enamel or the like. The insulated substrate is made by aprocedure such as the pressure sensitive adhesion method. theheabsensitive adhesion method. the adhesive varnish undercoating method.the water-sliding method or the like. After the insulated substrate isformed it is normally fired at a temperature of from 600 to l.000C forabout 1 hour in air. The process does not require an inert atmosphere.In the firing treatment the synthetic resins are decomposed to fugacitywithin the printing layer and the metals are melted and partiallyoxidized to form a calorific layer having a resistance of several il/sqcm to several KH/sq When the previously mentioned plastics are used ascoating materials over the calorific layer with the insulating layer.the coating operation is performed either by spreading a paint of aplastic solution on the calorific lay er or by covering the calorificlayer with a plas tic film coated with an adhesive which optionally canbe a heat melting adhesive. lf glass. glaze or the like is to be used asa coating material. a film of the paste which has been treated inadvance with a dispersed solution of the material may be subjected as acomposite to firing. Also. if one of the previously mentioned porousinorganic materials is used. it may be adhesively applied to thecalorific layer with a bonding agent. Moreover. glass. ceramics. tefion.silica or the like which are subject to evaporation at the firingtemperature employed. can be coated by means of a vacuum evaporationmethod.

As shown in FIG. 4. the panel-styled calorific layer 10 can beincorporated in a circuit containing variable resistance 16 and switch17. If switch 17 is turned ON" and current flows through the circuit.the panelstyled calorific device 10 commences to generate heat.Induction heating by high frequency waves is also available by use ofthe panel-styled calorific device 10.

The calorific device of the present invention has many various andwide-ranging uses such as in electric heating appliances for cookingwhich includes toasters. electric heaters. electric frying pans.electric heating plates. electric hot plates. table grills (home grill).electric ovens. electric cookpots. egg boilers. electric ranges.electric hot reservoirs. table ware dryers and the like: electricalapparatuses for heating such as electric stoves. electric foot warmers.electric blankets. electric hot-air-heaters. floor heaters. panelheaters. electric hot seats for toilets. electric heating chairs.electric heating desks and the like: household appliances such aselectric irons. trousers pressers (creas- 8 ers). electric waterheaters. immersion-type hot-water heaters. electric soldering irons.electric hair curlers. towl steamers. electric heating mirrors. ceramictablets. tablet dishes and the like: and other uses such as in steambaths. sauna baths. electric dryers for industrial and laboratory uses.heating furnaces. heat retainers for hot houses. and the like.

Having generally described this invention. a further understanding canbe obtained by reference to certain specific examples which are providedhereinfor purpose of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLE 1 The following materials were mixed in the quantities indicatedbelow:

A glass powder of a mixed. fired product of barium carbonate and boricacid in the ratio of 1:1 by weight was prepared; zinc powder (300 meshfree) was used as a metal powder; A polyacrylmethyl lacquer (Stlr byweight naphtha solution) was used as the synthetic oil. The rawmaterials were milled in a roller mill in the ratio below to form apaste:

glass powder: 20 parts by weight zinc powder: 80 parts by weightsynthetic oil: 12 parts by weight An enameled steel panel was used as asubstrate. The paste was plastered on the substrate to a thickness ofabout 150 u by means of a silk screen printing procedure. After thecoated panel had dried. it was subjected to firing at a maximumtemperature of 600 to 700C for 1 hour. After firing. it was allowed tocool and a calorific layer was formed. At both ends of the calorificlayer were attached electrodes of belt-shaped aluminium foil.

The surface of the calorific layer was painted with a 57% by weightbutanol-xylol mixed solution of butyrated methylolmelamine resin. Afterthe layer was painted. the product was cured by heating at 150C forminutes. The film on the coated panel had a thickness of about I00 u. Inthis manner. a panel-styled calorific device A was formed.

COMPARISON EXAMPLE l Several pastes were prepared using glass powder andzinc powder similar to the procedure of Example 1 in a variety of ratiosas shown in Table l.

TABLE 1 Paste No. l I 3 4 5 Glass powder (part/wt) 3t) S0 60 Zinc powder(partlwtl 70 60 50 40 30 From the data in Table 2. it is clear thatcalorific devices for practical purposes can not be obtained when thecontent of the glass powder in the paste exceeds 60% by weight becausethe resistance becomes too great. At glass powder contents less than 20%by weight the resistance values are also unsatisfactory.

EXAMPLE 2 A calorific paste was formed from a pulverized silica glasspowder and a synthetic oil comprising a mixture of 30 parts by weight ofethyl cellulose. 70 parts by weight. of pine oil and 10 parts by weightof dioctyl phthalate. The raw materials with silver were milled in amasher in the following ratio to prepare the paste.

glass powder parts by weight silver powder 1 25 parts by weightsynthetic oil parts by weight A ceramic plate was used as a substrate.The paste was painted on the substrate to a thickness of about 200u witha knife coater. After the plate was painted. it was dried. Subsequently.the conductive paste was ap plied in a belt-shape to both ends of thepaste film. Thereafter. the device was fired at a maximum temper atureof 850C for l hour. After the firing operation. the device was cooledand a panel-styled calorific layer having belt-shaped electrodes oneither end was formed.

A polyvinyl chloride film of 0.5 mm in thickness was adhered to thesurface of a calorific layer with an epoxide resin adhesive. By thisprocedure a paneLstyled calorific material B was obtained.

COMPARISON EXAMPLE 2 Several paste compositions containing variousratios of glass powder to silver powder were prepared as described inExample 2. The ratios are shown in Table 3.

Using the various pastes shown in Table 3. several diverse panel-styledcalorific devices were fabricated by the same procedure as used inExample 2. The firing procedure. however. was accomplished in a nitrogenatmosphere to prevent oxidation of the silver. Resistance values andsilver metal contents of the panelstyled calorific material B of Example2 and the panelstyled calorific materials of Comparison Example 2. areShown in Table 4.

TABLE 3 Resistance Value 8 fr 7 t4 9 fli'sqcml Siher Metal content ratiol'ipwt) 10 From the data in Table 4. it is clear that calorificmaterials can not be effectively attained for practical purposes whenthe metal content exceeds 97% by weight because the resistance valuesare too small.

EXAMPLE 3 A paste was prepared from a mixture of l5 parts by weight ofphosphate glass powder. parts by weight of a metal powder mixture of tinto copper to silver of 2:414 and 30 parts by weight of a synthetic oilcomprising 40% by weight solvesso No. I50 solution of TUF PRENE (Tradename of styrenebutadiene rubber. pre pared by the ASAHl KASEI CO). Theraw materials were milled in an attriter.

The paste prepared by the above procedure was printed on a pasteboardwhich was painted with water soluble dextrin by a screen printingprocedure. and was left to dry in air. The resulting dehydrated printinglayer was of a thickness of about 100 to u. The transfer which was papercured in this manner had a flexible printing layer and was easy to keepand transport.

The paste was transferred to a ceramic plate substrate by a watersliding method in which the coated paper was dipped in water with itsprinted surface upward. This configuration permitted the water solubledextrin to dissolve. which allowed the printing layer to separate fromthe pasteboard. The separated printing layer which had risen to thesurface of the water was removed from the water either by the substrateitself or by the use of a pincette. Thereafter. it was transferred tothe surface of the substrate. The transfer-printed substrate was firedat a temperature of 600 to 700C. After the substrate was cooled.belt-shaped aluminum foil was applied to both ends of the calorificlayer as electrodes.

A glass fiber mat was applied on the surface of the calorific layer witha urethane resin adhesive. By this procedure panel-styled calorificmaterial C was obtained. which had a metal content of 48% by weight anda resistance value of 30 fl/sq cm. It had substantial heat retainingproperties.

EXAMPLE 4 A paste was prepared from 40 parts by weight of a syntheticoil prepared from 5 parts by weight of ethyl ene glycol and 20 parts byweight of a hydroxyl-ethylcellulose solution which was added to I00parts by weight of a Copolymer emulsion of acryl-n-butyl and methacryln-butyl in mole ratio of l:3. 90 parts by weight of Zinc metal powderand l0 parts by weight of barium oxide glass powder. These raw materialswere milled in a ball mill.

The paste was coated on a release paper with a roller coater.Thereafter, the paste was dried leaving a film of 50 in thickness.

A cylindrically shaped enameled metal vessel was used as a substrate.The release paper upon which the film was coated was scrupulously fittedon the circumferential wall of the enameled metal vessel. whereby thefilm was pressure-adhered thereon. After removing the release paperafter the pressure-adhering steps. the film adhered firmly to thecircumferential wall and re mained there. Thereafter. a conductive pastewas coated in a belt-shape configuration on the upper and lower rims ofthe film. and a glaze was coated on the surface of the film. After thecoating had dried. the film was fired at 700 to 800C. By this procedurea glaze covered panel-styled calorific material D was obtained. Thecalorific material D had a metal content of 84)? and a resistance of 2Q/sq cm.

Having now fully described this invention. it will be apparent to one ofordinary skill in the art that many changes and modifications can bemade thereto without departing from the spirit or scope of the inventionas set forth herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A panel-styled calorific device which comprises:

a. a substrate b. a layer of calorific material prepared by mixing l.glass powder 2. a metal powder selected from the group consisting ofcopper. silver. gold. zinc. cadmium. aluminum. indium. thallium. tin.lead. antimony and bismuth. and

3. a synthetic oil comprising an organic solvent and at least onesynthetic resin selected from the group consisting of acr resins.methacrylic resins. vinyl acetate resins. styrol resins. vinyl etherresins. vinyl chloride resins. vinylidene chloride resins. vinylpyrrolidone resins. polyethylene. polypropylene. polyvinyl alcohol.acetal resins. butyral resins. phenol resins. alkyol resins. melamineresins. polyamide resins. polyurethane resins. mcthylcellulose.hydroxyethyl cellulose. carboxymethyl cellulose. ethyl cellulose.cellulose nitrate. cellulose acetate. cellulose butyrate. styrenebutadiene rubbers. acrylonitrile-butadiene rubber. isoprene rubber.butyl rubber. polybutadiene rubber. polychloroprene rubber.ethylenepropylene rubber. thiokol rubber. natural rubber and reclaimedrubbers thereof. petroleum resins. cumarone resins. terpeno resins.rosin and derivatives thereof. starch. denatured starch. proteins anddenatured proteins. and firing the mixture at a temperature above themelting point of sand metal powder thereby partially oxidizing saidmetal powder on said substrate. and

c. a protective coating over said calorific layer. said metal powderbeing present in the mixture in an amount ranging from 97 to 2 5% byweight.

2. The panel-styled calorific device of claim 1, wherein said substrateis an enameled metal panel.

3. The panel-styled calorific device of claim 1. wherein said protectivecoating is a film formed from a synthetic composition whose majorcomponent is a melamine resin.

4. A method for fabricating a panel-styled calorific device whichcomprises:

a. coating a substrate with a paste comprising a mixture of a glasspowder. a metal powder selected from the group consisting of Copper.zinc. silver gold. cadmium. chromium. indium. thallium. tin. lead.antimony and bismuth. and a synthetic oil comprising an organic solventand at least one synthetic resin selected from the group consisting ofacryl resins. methacrylic resins. vinyl acetate resins. styrol resins.vinyl ether resins. vinyl chloride resins. vinylidene chloride resins.vinyl pyrrolidone resins. polyethylene. polypropylene. polyvinylalcohol. acetal resins. butyral resins. phenol resins. alkyol resins.melamine resins. polyamide resins. polyurethane resins. methylcellulosc.hydroxyethyl cellulose. carboxymethyl cellulose. ethyl cellulose.cellulose nitrate. cellulose acetate. cellulose buty rate. sty renebutadiene rubbers. acrylonitrilebutadiene rubber. isoprene rubber. butylrubber. polybutadiene rubber. polychloroprene rubber. ethylene-propylenerubber. thiokol rubber. natural rubber and reclaimed rubbers thereof.pctroleum resins. cumarone resins. terpeno resins. rosin and derivativesthereof. starch. denatured starch. proteins and denatured proteins.

. firing the mixture at a temperature above the melting point of saidmetal powder thereby partially oxidizing said metal powder on saidsubstrate. and

c. coating the tired mixture of step (b) with a protective material saidmetal powder being present in said mixture in an amount of from 86 to27% by weight.

5. The method of claim 4, wherein said paste is coated on said substrateby coating the paste on a transfer paper and then transferring saidcoated paste to said substrate.

6. The method of claim 4. wherein said protective material is a film ofmelamine resin.

7. The method of claim 4, wherein said paste comprises a mixture of l()to parts by weight of said synthetic oil per parts by weight of amixture of 0 to 60% by weight of said glass and 100 to 40% by weight ofsaid metal powder.

8. The method of claim 7, wherein the glass transition temperature ofthe synthetic resin of said synthetic oil is less than 20C.

1. A PANEL-STYLED CALORIFIC DEVICE WHICH COMPRISES: A. A SUBSTRATE B. ALAYER OF CALORIFIC MATERIAL PREPARED BY MIXING
 1. GLASS POWDER
 2. AMETAL POWDER SELECTED FROM THE GROUP CONSISTING OF COPPER, SILVER, GOLD,ZINC, CADMIUM, ALUMINUM, INDIUM, THALLIUM, TIN, LEAD, ANTIMONY ANDBISMUTH, AND
 2. The panel-styled calorific device of claim 1, whereinsaid substrate is an enameled metal panel.
 2. a metal powder selectedfrom the group consisting of copper, silver, gold, zinc, cadmium,aluminum, indium, thallium, tin, lead, antimony and bismuth, and
 3. asynthetic oil comprising an organic solvent and at least one syntheticresin selected from the group conSisting of acryl resins, methacrylicresins, vinyl acetate resins, styrol resins, vinyl ether resins, vinylchloride resins, vinylidene chloride resins, vinyl pyrrolidone resins,polyethylene, polypropylene, polyvinyl alcohol, acetal resins, butyralresins, phenol resins, alkyol resins, melamine resins, polyamide resins,polyurethane resins, methylcellulose, hydroxyethyl cellulose,carboxymethyl cellulose, ethyl cellulose, cellulose nitrate, celluloseacetate, cellulose butyrate, styrene butadiene rubbers,acrylonitrile-butadiene rubber, isoprene rubber, butyl rubber,polybutadiene rubber, polychloroprene rubber, ethylene-propylene rubber,thiokol rubber, natural rubber and reclaimed rubbers thereof, petroleumresins, cumarone resins, terpeno resins, rosin and derivatives thereof,starch, denatured starch, proteins and denatured proteins, and firingthe mixture at a temperature above the melting point of sand metalpowder thereby partially oxidizing said metal powder on said substrate,and c. a protective coating over said calorific layer, said metal powderbeing present in the mixture in an amount ranging from 97 to 27% byweight.
 3. The panel-styled calorific device of claim 1, wherein saidprotective coating is a film formed from a synthetic composition whosemajor component is a melamine resin.
 3. A SYNTHETIC OIL COMPRISING ANORGANIC SOLVENT AND AT LEAST ONE SYNTHETIC RESIN SELECTED FROM THE GROUPCONSISTING OF ACRYL RESINS, METHACRYLIC RESINS, VINYL ACETATE RESINS,STYROL RESINS, VINYL ETHER RESINS, VINYL CHLORIDE RESINS, VINYLIDENECHLORIDE RESINS, VINYL PYRROLIDONE RESINS, POLYETHYLENE, POLYPROPYLENE,POLYVINYL ALCOHOL, ACETAL RESINS, BUTYRAL RESINS, PHENOL RESINS, ALKYOLRESINS, MELAMINE RESINS, POLYAMIDE RESINS, POLYURETHANE RESINS,METHYLCELLULOSE, HYDROXYETHYL CELLULOSE, CARBOXYMETHYL CELLULOSE, ETHYLCELLULOSE, CELLULOSE NITRATE, CELLULOSE ACETATE, CELLULOSE BUTYRATE,STYRENE BUTADIENE RUBBERS, ACRYLONITRILE-BUTADIENE RUBBER, ISOPRENERUBBER, BUTYL RUBBER, POLYBUTADIENE RUBBER, POLYCHLOROPRENE RUBBER,ETHYLENE-PROPYLENE RUBBER, THIOKOL RUBBER, NATURAL RUBBER AND RECLAIMEDRUBBERS THEREOF, PETROLEUM RESINS, CUMARONE RESINS, TORPENO RESINS,ROSIN AND DERIVATIVES THEREOF, STARCH, DENATURATED STARCH, PROTEINS ANDDENATURATED PROTEINS, AND FIRING THE MIXTURE AT A TEMPERATURE ABOVE THEMELTING POINT OF SAND METAL POWDER THEREBY PARTIALLY OXIDIZING SAIDMETAL POWDER ON SAID SUBSTRATE, AND C. A PROTECTIVE COATING OVER SAIDCALORIFIC LAYER, SAID METAL POWDER BEING PRESENT IN THE MIXTURE IN ANAMOUNT RANGING FROM 97 T 27% BY WEIGHT.
 4. A METHOD FOR FABRICATING APANEL-STYLED CALORIFIC DEVICE WHICH COMPRISES: A. COATING A SUBSTRATEWITH A PASTE COMPRISING A MIXTURE OF A GLASS POWDER, A METAL POWDERSELECTED FROM THE GROUP CONSISTING OF COPPER, ZINC, SILVER, GOLD,CADMIUM, CHROMIUM, INDIUM, THALLIUM, TIN, LEAD, ANTIMONY AND BISMUTH,AND A SYNTHETIC OIL COMPRISING AN ORGANIC SOLVENT AND AT LEAST ONESYNTHETIC RESIN SELECTED FROM THE GROUP CONSISTING OF ACRYL RESINS,METHACRYLIC RESINS, VINYL ACETATE RESINS, STYROL RESINS, VINYL ETHERRESINS, VINYL CHLORIDE RESINS, VINYLIDENE CHLORIDE RESINS, VINYLPYRROLIDONE RESINS, POLYETHYLENE, POLYPROPYLENE, POLYVINYL ALCOHOL,ACETAL RESINS, BUTYRAL RESINS, PHENOL RESINS, ALKYOL RESINS, MELAMINERESINS, POLYAMIDE RESINS, POLYURETHANE RESINS, METHYLCELLULOSE,HYDROXYETHYL CELLULOSE, CARBOXYMETHYL CELLULOSE, ETHYL CELLULOSE,CELLULOSE NITRATE, CELLULOSE ACETATE, CELLULOSE BUTYRATE, STYRENEBUTADIENE RUBBERS, ACRYLONITRILEBUTADIENE RUBBER, ISOPRENE RUBBER, BUTYLRUBBER, POLYBUTADIENE RUBBER, POLYCHLOROPRENE RUBBER, ETHYLENEPROPYLENERUBBER, THIOKOL RUBBER, NATURAL RUBBER AND RECLAIMED RUBBERS THEREOF,PETROLEUM RESINS, CUMARONE RESINS, TERPENO RESINS, ROSIN AND DERIVATIVESTHEREOF, STARCH, DENATURED STARCH, PROTEINS AND DENATURED PROTEINS, B.FIRING THE MIXTURE AT A TEMPERATURE ABOVE THE MELTING POINT OF SAIDMETAL POWDER THEREBY PARTIALLY OXIDIZING SAID METAL POWDER ON SAIDSUBSTRATE, AND C. COATING THE FIRED MIXTURE OF STEP (B) WITH APROTECTIVE MATERIAL SAID METAL POWDER BEING PRESENT IN SAID MIXTURE INAN AMOUNT OF FROM 86 TO 27% BY WEIGHT.
 5. The method of claim 4, whereinsaid paste is coated on said substrate by coating the paste on atransfer paper and then transferring said coated paste to saidsubstrate.
 6. The method of claim 4, wherein said protective material isa film of melamine resin.
 7. The method of claim 4, wherein said pastecomprises a mixture of 10 to 75 parts by weight of said synthetic oilper 100 parts by weight of a mixture of 0 to 60% by weight of said glassand 100 to 40% by weight of said metal powder.
 8. The method of claim 7,wherein the glass transition temperature of the synthetic resin of saidsynthetic oil is less than 20*C.